The conventional circuit breaker uses a fuse between the switch and the circuit such that when there is an electrical overload, the fuse will first melt before the overload causes damages. However, if the fuse is not properly installed or an improper fuse is used the overload current cannot melt the fuse and a disaster can be resulted. U.S. Pat. Nos. 5,262,748, 4,167,720, 4,937,548, 5,223,813, 5,451,729, and 5,558,211 disclose different types of circuit breakers which commonly include a complicated mechanism to drive the bimetallic plate which is expected to be deformed and bent when overload in current. Nevertheless, it is noted that the bimetallic plate does not completely deformed as desired because it is not passable to freely deformed, and is still in contact with the terminal so that sparks could be produced and therefore cause disaster.
Therefore, it is desired to have a protection mechanism for a switch device that includes a push member for pushing the bimetallic plate to its “ON” position and the push member can only be rotated in one direction which produces a space to allow the bimetallic plate to be completely deformed when the current is overload so as to resolve the shortcomings of the conventional switch devices.